Phase-dependent ion-to-electron transducing efficiency of WS₂ nanosheets for an all-solid-state potentiometric...

Ultrathin metallic WS₂ (M-WS₂) nanosheets and semiconductive WS₂ (S-WS₂) nanosheets were exfoliated and for the first time employed as ion-to-electron transducing layer to construct an all-solid-state ion-selective electrode. Importantly, we found that the transducing efficiency of WS₂ nanosheet-based solid-contact layer is phase-dependent. The M-WS₂ nanosheets with larger content of 1 T-phase structure exhibit higher transducing efficiency than S-WS₂ nanosheets, which can be ascribed to the remarkable conductivity of M-WS₂ nanosheets. In order to demonstrate the excellent properties of the M-WS₂ nanosheet-based tranducing layer, an all-solid-state calcium ion potentiometric sensor was constructed as the model. As expected, a Nernstian response (27.41 mV per decade, R² = 0.9998) with a wide linear range of 1.0 × 10^-5.0 to 1.0 × 10^-2.0 M and a limit of detection of 2.0 μM was obtained. The developed all-solid-state potentiometric sensor using M-WS₂ nanosheets as ion-to-electron transducing layer is expected to bring new progress for routine detection in various fields. Graphical Abstract Schematic illustration of the introduction of WS₂ nanosheets with different phase structures as a new-generation solid-contact ion-to-electron transducing layer for all-solid-state potentiometric sensors.